9 OPTICAL, ELECTRIC, WEIGHING, MEASURING, SIGNALING AND CHECKING APPARATUS AND INSTRUMENTS, NAMELY BALANCES, MICROBALANCES, SURFACE AREA ANALYZERS, POROSITY ANALYZERS; APPARATUS FOR MEASURING MASS CHANGES OR MATERIAL TRANSFER, NAMELY, MAGNETIC SUSPENSION BALANCES, RECORDING MICROBALANCES, CALORIMETERS, MASS FLOW CONTROLLERS, MASS SPECTROMETERS; APPARATUS FOR THE EXECUTION OF SORPTION MEASURING, NAMELY GAS AND VAPOR DOSING SYSTEMS; SORPTION ANALYZERS, GRAVIMETRIC ADSORPTION AND ABSORPTION ANALYZERS, VOLUMETRIC ADSORPTION AND ABSORPTION ANALYZERS, CARRIER GAS FLOW ADSORPTION ANALYZERS, FURNACES FOR LABORATORY EXPERIMENTS; TEMPERATURE CONDUCTIVITY DETECTORS; APPARATUS FOR SURFACE CHARACTERIZATION, NAMELY VOLUMETRIC PHYSISORPTION AND CHEMISORPTION ANALYZERS, TPD ANALYZERS, TPR ANALYZERS, TPO ANALYZERS AND METAL DISPERSION ANALYZERS; APPARATUS FOR MEASURING PARTICLE SIZES, PORE SIZES AND SPECIFIC SURFACES, NAMELY VOLUMETRIC, GRAVIMETRIC AND CARRIER GAS FLOW SORPTION MEASURING ANALYZERS